1. Field of the Invention
The present invention relates to a color hologram recording medium, more specifically to a color hologram recording medium which includes volume holograms containing reconstruction patterns recorded in a plurality of wavelengths, and can have a large variety of designs and artistic characters.
2. Related Art
It is conventionally known that a color hologram recording medium includes volume holograms containing reconstruction patterns of three colors, R (red), G (green) and B (blue). The volume holograms are multi-recorded or overlapped for additive color mixing. It is also known that a color hologram recording medium includes R picture elements or dots, G picture elements or dots and B picture elements or dots which are juxtaposed with one another for additive color mixing resorting to area ratios among them. It has been also proposed by the inventors of the present invention in Japanese Patent Application No. 190970/1997 (Japanese Patent Laid-Open Publication No. 133611/1998) that neutral tints are provided by dot area ratios in such color hologram recording mediums.
However, in the conventional color hologram recording mediums, the volume holograms contain reconstruction patterns of the respective colors so that the reconstruction patterns are reconstructed in the same plane. Accordingly, the conventional color hologram recording mediums cannot provide a variety of designs and artistic characters that, for example, recorded color reconstruction patterns vary depending on watched directions.
The present invention has been made in light of such disadvantage of the conventional color hologram recording mediums. An object of the present invention is to provide a color respective colors recorded so that the reconstruction patterns of the respective colors can be reconstructed at positions different from each other. Accordingly to the present invention, a wide variety of designs and artistic characters that, for example, the recorded color reconstruction patterns vary depending on watched directions can be provided.
The color hologram recording medium according to the present invention includes a plurality of volume holograms respectively including reconstruction patterns independent from each other, for diffracting light of wavelengths different from each other. The reconstruction patterns of the volume holograms are reconstructed at positions, which are different from each other.
In the above-described color hologram recording medium, it is preferable that the volume holograms are multi-recorded in a recording sensitive material. Also, it is preferable that each of the volume holograms is recorded in each of a plurality of sensitive materials to be laid one on another.
In the above-described color recording medium, it is preferable that the reconstruction patterns of the volume holograms are plane patterns. Also, it is preferable that the plane patterns are parallel with each other. In addition, it is preferable that the volume holograms are reflection/scattering holograms.
In the above-described color recording medium, it is preferable that the reconstruction patterns of the volume holograms are partially overlapped on each other so as to exhibit a neutral tint by additive color mixing of the reconstruction patterns in case that the volume holograms are observed in at least one direction. Also, it is preferable that at least one of the volume holograms has the reconstruction pattern formed in dots.
The process for fabricating the color hologram recording medium according to the present invention includes the step of preparing a plurality of first original plates respectively recording volume holograms which diffract light of wavelengths holograms recorded in the first original plates into second original plates, which are respectively spaced from the first original plates by distances which are different from each other; and the step of multi-recording the volume holograms recorded in the second original plates into a recording sensitive material to fabricate a color hologram recording medium.
The process for fabricating the color hologram recording medium according to the present invention includes the step of preparing a plurality of first original plates respectively recording volume holograms which diffract light of wavelengths different from each other; the step of recording the volume holograms recorded in the first original plates into second original plates which are respectively spaced from the first original plates by distances which are different from each other; the step of recording the volume holograms recorded in the second original plates respectively into recording sensitive materials spaced from the second original plates by a prescribed distance; and the step of laying the respective recording sensitive materials one on another to fabricate a color hologram recording medium.
According to the present invention, the reconstruction patterns of the volume holograms are multi-recorded or overlapped on each other so that the reconstruction patterns can be reconstructed at positions different from each other. Therefore, the reconstruction patterns are visible separately at positions which are depth-wise different from one another. The general pattern of the reconstruction patterns, and the shapes and the layout of the tint regions, that is the overlapped regions between the reconstruction patterns, change when an observation position is displaced. Thus, the color hologram recording medium having a wide variety of designs and artistic characters can be provided.